Ball game ball

ABSTRACT

A ball for a ball game includes an elastic bladder having the form of a spherical hollow body into which compressed air is charged, a reinforced layer formed on a whole surface of the bladder, and a plurality of leather panels bonded onto the reinforced layer directly or through a cover rubber layer, wherein a peripheral edge portion of the leather panel is folded toward an inside and a thickness adjusting member for eliminating a difference in step caused by the folding of the leather panel is caused to be bonded onto the back of the leather panel surrounded by the folded portion of the leather panel.

TECHNICAL FIELD

The present invention relates to ball for ball games such as a soccerball, a handball, a volleyball and the like.

BACKGROUND ART

Conventionally, there have been two kinds of balls for ball games havingan air charging structure, for example, a laminated ball and a handstitched ball.

As disclosed in the specification of U.S. Pat. No. 4,333,648, forexample, the laminated ball comprises a rubber bladder made of airimpermeable rubber and having a spherical hollow body into whichcompressed air is charged through a valve, a reinforced layer formed bywinding a fiber such as a nylon filament having several thousands metersonto the bladder in every circumferential direction in order tostabilize the quality of the ball (weight, size, sphericity, durability,shape maintenance, and an enhancement in strength for a change with thepassage of time), a cover rubber layer made of a thin vulcanized rubberlayer bonded onto the reinforced layer, and an outermost layer includinga plurality of leather panels bonded onto the cover rubber layer. Thecover rubber layer has the function of tightly bonding the leather panelonto the ball. An artificial leather panel or a natural leather panel isused for the leather panel. In many cases, an end of the back of theleather panel is usually cut obliquely (which is referred to asdiagonally cutting), and a trench having an almost V shape is formed ona leather panel joint.

Since the ball having such a structure can be mechanically manufactured,it has good productivity (a small variation in weight and size) and isgenerally inexpensive. In addition, such a ball is excellent insphericity and durability. On the other hand, the trench formed on thepanel joint has a great width (usually about 8 mm) and has a shallowdepth (usually about 1 mm). Therefore, there is a problem in that an airresistance cannot be reduced and a flight cannot be increased. There isa further problem in that the ball has poor gripping properties and ishard to grip.

The hand stitched ball has a structure in which the same bladder asdescribed above is housed in an outermost layer having a spherical shapewhich is formed by folding edges of a plurality of leather panels towardthe inside and sewing them together with a thread (usually about 10000deniers). The same artificial leather or natural leather is used for theleather panel. A backing member formed by sticking a plurality of wovenfabrics is usually bonded onto the back of the leather panel. Morespecifically, the woven fabrics are bonded onto the back of the leatherpanel with an adhesive such as a latex paste, thereby reinforcing theleather panel. The hand stitched ball having such a structure has beendisclosed in Japanese Unexamined Patent Publication No. 19516/1997, forexample.

According to the ball having such a structure, the leather panel isfolded toward the inside together with the backing member. Therefore, atrench to be formed in this portion has a smaller width of about 2.5 mmand a greater depth of about 2.0 mm than in the laminated ball.Therefore, the ball has advantages that an air resistance can bereduced, a flight can be increased, and excellent gripping properties,that is, easiness to grip by hands, good operability and excellent ballcontrollability can be obtained. However, since the ball is a solid, itcannot be stitched by a machine but should be stitched by hands. Forthis reason, there is a problem in that a lot of skill is required, anindividual variation is increased and productivity is poor. In addition,the quality is also uneven, and variations in weight, size andsphericity are easily generated.

When an internal pressure of about 1.0 kg/cm² and shock such as kick areapplied to the ball, force or shock of several hundreds kilograms, ormore is applied. For this reason, there is a drawback that seam openingis caused. Consequently, the size of the ball is increased more than thestandard or is deformed in some cases. In the worst case, there is adanger that the thread might be broken or be unknotted due to the shockto cause the bladder to project. The durability of the hand stitchedball is usually about ½ to ⅓ of that of the laminated ball.

It is an object of the present invention to improve aerodynamiccharacteristics and the like of the structure of the laminated ball. Thepresent invention solves the above-mentioned problems by forming thesame trench as in the hand stitched ball on the joint of the leatherpanel of the ball, and realizes a ball having the flight, grippingproperties and ball controllability of the hand stitched ball whilekeeping the quality of the laminated ball (weight, size, sphericity,durability, shape maintenance, and an enhancement in strength for achange with the passage of time).

DISCLOSURE OF THE INVENTION

The present invention provides a ball for a ball game comprising anelastic bladder having the form of a spherical hollow body into whichcompressed air is charged, a reinforced layer formed on a whole surfaceof the bladder, and a plurality of leather panels bonded onto thereinforced layer directly or through a cover rubber layer, wherein aperipheral edge portion of the leather panel is folded toward an insideand a thickness adjusting member bonded onto the back of the leatherpanel surrounded by the folded portion of the leather panel. Accordingto such a structure, a trench having the same shape as the shape of ahand stitched ball is formed on a joint of the adjacent leather panels.The trench reduces air resistance, enhances gripping properties andgives easiness to grip the ball. Accordingly, operability and ballcontrollability can be enhanced. By the existence of the thicknessadjusting member, the back of the leather panel is a flat face.Consequently, the difference in step caused by the folding does notappear on the surface of the leather panel.

A ball for a ball game according to the present invention ischaracterized in that the peripheral edge portion of the leather panelis folded toward the inside by about 180 degrees. According to such astructure, the folded portion of the leather panel is bonded onto thecover rubber layer or the reinforced layer. Therefore, even if peelingis caused on the panel joint, there is little possibility that thefolded portion might be turned over to appear on the surface of theball.

A ball for a ball game according to the present invention ischaracterized in that the peripheral edge portion of the leather panelis folded toward the inside by about 90 degrees. According to such astructure, the folded portion of the leather panel is not insertedbetween the cover rubber layer or the reinforced layer and the thicknessadjusting member. Therefore, there is no possibility that the thicknessof the folded portion might appear as an irregularity on the surface ofthe leather panel.

A ball for a ball game according to the present invention ischaracterized in that the leather panel is bonded in the joint to theadjacent leather panel. According to such a structure, water can beprevented from entering the joint of the leather panels. In addition,the peeling of the leather panel can be prevented so that durability canbe enhanced.

A ball for a ball game according to the present invention ischaracterized in that a notch is formed in the folded portion of theleather panel. According to such a structure, the folding can easily beperformed like a curved line.

A ball for a ball game according to the present invention ischaracterized in that the thickness adjusting member is made of a wovenfabric. According to such a structure, the bias effect of the wovenfabric can prevent the ball from being deformed when external force isapplied to the ball. Also in the case where such external force todamage the leather panel is applied, the force is intercepted by thewoven fabric so that the bladder can be protected.

A ball for a ball game according to the present invention ischaracterized in that the thickness adjusting member is made of a shockabsorbing member. According to such a structure, the external forceapplied to the ball is absorbed and relieved by the shock absorbingmember. Consequently, a feeling can become soft when the ball hits ahuman body.

A ball for a ball game according to the present invention ischaracterized in that the thickness adjusting member has a laminationstructure of the woven fabric and the shock absorbing member. Accordingto such a structure, the shock absorbing member and the bladder whichare provided on the inside can be protected by the woven fabric, and theshock absorbing function can be obtained by the shock absorbing member.

A ball for a ball game according to the present invention ischaracterized in that the shock absorbing member is formed of a foamingmember, a nonwoven fabric, a bulky woven fabric or a honeycombconstruction member. According to such a structure, the shock absorbingmember and the bladder which are provided on the inside can be protectedby the woven fabric, and the shock absorbing function can be obtained bythe shock absorbing member.

A ball for a ball game according to the present invention ischaracterized in that the reinforcing member is provided between theleather panel and the thickness adjusting member. According to such astructure, when force to extend the leather panel is applied by theinternal pressure of the bladder, the reinforced member inhibits theextension so that the expansion of the ball can be suppressed. Also inthe case where the external force to damage the leather panel isapplied, the force can be intercepted by the reinforced layer so thatthe bladder can be protected.

A ball for a ball game according to the present invention ischaracterized in that the reinforced layer is made of a polyester film,a PVC film, a polyethylene film or a polypropylene film. According tosuch a structure, it is possible to obtain a reinforced layer havingflexibility, light weight and small thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a ball for a ball gave according toan embodiment of the present invention, a part of which being cut away;

FIG. 2 is a sectional view taken along the line A—A in FIG. 1;

FIG. 3 is a plan view showing the back of a leather panel;

FIG. 4 is a sectional view showing a leather panel according to theembodiment;

FIG. 5 is a sectional view showing a leather panel according to anotherembodiment;

FIG. 6 is a sectional view showing a leather panel according to yetanother embodiment;

FIG. 7 is a sectional view showing a leather panel according to afurther embodiment;

FIG. 8 is a view illustrating a method for bonding the leather panelonto a thickness adjusting member;

FIG. 9 is a view illustrating the method for bonding the leather panelonto the thickness adjusting member;

FIG. 10 is a view illustrating the method for bonding the leather panelonto the thickness adjusting member;

FIG. 11 is a sectional view showing a leather panel according to afurther embodiment;

FIG. 12 is a sectional view showing a leather panel according to afurther embodiment;

FIG. 13 is a sectional view showing a leather panel according to afurther embodiment;

FIG. 14 is a plan view illustrating a leather panel according to afurther embodiment;

FIG. 15 is a graph representing a flight; and

FIG. 16 is a graph representing a curve characteristic.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, a ball for a ball game according to an embodiment of the presentinvention will be described in detail with reference to the accompanyingdrawings.

EMBODIMENT 1

In FIG. 1, the reference numeral 1 denotes an example of a soccer balland the reference numeral 2 denotes a bladder made of an elasticmaterial having air impermeability such as butyl rubber in the form of aspherical hollow body, into which compressed air is charged. Thereference numeral 3 denotes a valve for injecting the compressed airinto the bladder 2, an internal pressure being set to about 1.0 kg/cm².The reference numeral 4 denotes a reinforced member formed by winding afiber, for example, a nylon filament having a length of about 3000 monto the surface of the bladder 2 in every direction on a circumference.The quality of the ball can be enhanced and stabilized by the reinforcedlayer 4 as described above. The reinforced layer 4 can be formed byoverlapping a plurality of woven fabrics such as cotton fabrics togetherand sticking them onto the surface of the bladder 2 or sewing the wovenfabrics spherically as well as winding a thread as described above. Inaddition, elastomer such as polyurethane, polyester, nylon orpolyolefine which is molded spherically or rubber blended with areinforced fiber can be used as the bladder. The bladder having such astructure itself has a reinforcing function. Therefore, a specialreinforced layer does not need to be provided. The reference numeral 5denotes a cover rubber layer made of natural rubber or the like which isformed on the reinforced layer 4, and the reference numerals 6 denote aleather panel bonded onto the cover rubber layer 5 with an adhesive suchas a CR (chloroprene) based adhesive. A thickness adjusting member 10which will be described below is bonded onto the back of the leatherpanel 6.

In the present embodiment, a whole spherical surface is covered withtwelve pentagonal panels and twenty hexagonal panels onto which thethickness adjusting member 10 is bonded. The cover rubber layer 5functions to strengthen the bonding of the leather panel 6 onto thethickness adjusting member 10. It is also possible to employ a structurein which the leather panel 6 is directly bonded onto the reinforcedlayer 4. In particular, if the sticking structure of the woven fabric orthe sewing structure of the woven fabric is employed as the reinforcedlayer 4, the cover rubber layer 5 is omitted in many cases. Furthermore,the cover rubber layer 5 can also be formed only on the joints of theleather panels 6. An artificial leather (including a synthetic leather,and so forth) or a natural leather is used for the leather panels 6. Abacking member made of a woven fabric or the like for reinforcement canalso be bonded onto the back of the leather panel 6. In this case, theleather panel 6 is used including the backing member.

As shown in FIGS. 2 and 3, the leather panels 6 have ends thereof foldedtoward the back side by about 180 degrees. Therefore, the bonded ends ofthe leather panels 6 have almost semicircular sections, on which atrench 7 having the same shape as the shape of the trench of a handstitched ball is formed. When the leather panels 6 are to be bonded ontothe cover rubber layer 5, the butt joints of the leather panels 6 may bebonded. With such a structure, the leather panels 6 are not separated onthe joints thereof so that water or the like can be prevented fromentering from a stuck portion. Furthermore, the ball itself can beprevented from expanding. Consequently, durability can be enhanced.

In the case where the end of the leather panel 6 is to be folded towardthe back side, folded portions 8 need to be provided with V-shapednotches 9 in the middle thereof as shown in FIG. 3. The reason is thateach of sides S of the polygonal leather panel 6 is curved slightlyoutward along the spherical surface. Each of the folded portions 6 canhave a width of about 1 to 10 mm, more preferably, about 3 mm.

The reference numeral 10 denotes a thickness adjusting member which isbonded onto a region surrounded by the folded portions 8 on the back ofthe leather panel 6 described above and is set to almost the samethickness as the thickness of the leather panel 6. More specifically,the leather panel 6 usually has a thickness of about 1.6 to 1.8 mm.Therefore, the thickness adjusting member 10 is also set to the samethickness. Consequently, a difference in step generated between thefolded portions 8 and the back of the leather panel 6 can be eliminated.One or more woven fabrics can be used for the thickness adjusting member10. In the case where a plurality of woven fabrics are used, they areoverlapped and bonded with a latex paste or the like. Cotton fabrics ormixed to spinning of cotton and polyester is usually suitable for thewoven fabric. If three or four woven fabrics are overlapped, theabove-mentioned thickness can be obtained.

In a laminated ball, a shape thereof such as sphericity can be kept bythe reinforced layer 4. Therefore, in the case where the leather panel 6is bonded onto the reinforced layer 4 directly or through the coverrubber layer 5, the leather panel 6 side is bent along the difference instep of the folded portions 8 and is bonded onto the reinforced layer 4side when the thickness adjusting member 10 is not provided.Consequently, there is a problem in that a smooth spherical surfacecannot be obtained. The thickness adjusting member 10 solves theproblem, and changes the back of the leather panel 6 into a flat face sothat the surface thereof is therefore made smooth.

FIG. 4 shows a structure in which three woven fabrics 11, 11, 11 arestuck together to form the thickness adjusting member 10. The wovenfabric 11 has a continuous waveform structure in which a warp (a warpyarn) and a weft (a weft yarn) are caused to intersect each other to sewrespective upper or lower sides each other. In the case where the wovenfabric 11 is stretched in a direction having an angle of 45 degrees withrespect to the warp and the weft, great expanding action can be obtainedwhich is referred to as a bias effect. When external force is applied tothe ball, the bias effect of the woven fabric 11 does not prevent theball expanding according to the external force from being deformed.Moreover, since the woven fabric 11 has great tensile strength in thedirections of the warp and the weft, it also has the function ofstrengthening the leather panel 6. Furthermore, also in the case wheresuch external force as to damage and break the leather panel 6 isapplied, the same force is intercepted by the woven fabric 11.Therefore, the bladder 2 is rarely broken.

FIG. 5 shows a structure in which the shock absorbing member 12 is usedfor the thickness adjusting member 10 in place of the woven fabric 11. Afoaming member made of chloroprene (CR), polyurethane (PV),ethylene-vinyl acetate copolymer (EVA), polyethylene, polyvinyl chloride(PVC), natural rubber latex, synthetic rubber latex, polystyrene,polyolefine, ethylene-propylene-diene ternary copolymer rubber (EPDM) orthe like, a nonwoven fabric, a three-dimensional bulky woven fabric or ahoneycomb construction member is suitable for the material of the shockabsorbing member 12, for example. A sheet such as the foaming member orthe like is bonded onto the back of the leather panel 6 to eliminate thedifference in step of the folded portion 8. In addition to theabove-mentioned example, the lamination structure of the woven fabric 11and the shock absorbing member 12 can also be employed for the thicknessadjusting member 10. The bulky woven fabric includes plural layers inwhich a weft is entangled in the woven fabrics of respective layers andhas a three-dimensional soft structure. The honeycomb constructionmember is obtained by punching a nonwoven fabric or sponge (a foamingmember of polyurethane, EPDM or chloroprene rubber) in the form of ahoneycomb.

FIG. 6 shows a structure in which the reinforced layer 13 is providedbetween the leather panel 6 and the thickness adjusting member 10. Apolyester film, a PVC film, a polyethylene film and a polypropylene filmare suitable for the material of the reinforced layer 13. The reason isthat each of these films can be formed with great tensile strength,flexibility, light weight and small thickness. In the case where theshock absorbing member 12 is used as the thickness adjusting member 10in place of the woven fabric 11, the reinforced layer 13 is moreeffective. The reason is that the shock absorbing member 12 has smallermechanical strength than the mechanical strength of the woven fabric 11.

FIG. 7 shows another embodiment in which the peripheral edge portion ofa leather panel 14 is folded toward an inside by about 90 degrees with acorner portion rounded and the side face of a thickness adjusting member15 is covered with the folded portion. A backing member such as a wovenfabric for reinforcement may be fixed to the back of the leather panel14 in the same manner as the above-mentioned leather panel 6. In thiscase, the leather panel 14 is used including such a backing member. Thethickness adjusting member 15 has a two-layered structure of a wovenfabric 16 and a shock absorbing member 17. The woven fabric 16 can bemade of the same material as the material of the above-mentionedthickness adjusting member 10, and can have one or two woven fabricsoverlapped. The shock absorbing member 17 can also be made of the samematerial as the material of the above-mentioned shock absorbing member12. These materials are bonded to each other with an adhesive such as anatural latex, a chloroprene (CR) based adhesive, a polyurethane (PU)based adhesive or the like, and is bonded onto the back of the leatherpanel 14. The leather panel 14 onto which the thickness adjusting member15 is bonded is bonded onto the cover rubber layer 6 with the CR basedadhesive in the same manner as in the above-mentioned example. The wholeleather panel 14 can have a thickness of 2 to 10 mm, and the shockabsorbing member 17 can have a thickness of 1 to 7 mm. With such astructure, a trench 7 is formed on the peripheral edge of the leatherpanel 14 which is bent at an angle of about 90 degrees. In order toprevent the joint of the leather panel 14 on which the trench 7 is to beformed from opening, the joint is bonded together with the PU basedadhesive or the like. Consequently, water can be prevented from enteringfrom a butt joint. In addition, the joint does not open. Therefore,constant beauty can be kept for a long period of time. Moreover, thepeeling of the leather panel 14 and the thickness adjusting member 15can be prevented so that the durability of the ball can be enhanced.

FIGS. 8 to 10 show a method for bonding the leather panel 14 and thethickness adjusting member 15. For example, the thickness adjustingmember 15, that is, the woven fabric 16 and the shock absorbing member17 are provided in turn on the back of the leather panel 14 cut into ahexagon and are bonded together with an adhesive such as the naturallatex, the CR based adhesive, the PU based adhesive or the like. Afolded portion 19 for covering the thickness adjusting ember 15 isformed on the peripheral edge portion of the leather panel 14. Eachcorner portion of the leather panel 14 is cut with roundness in such amanner that a sharp portion is not formed by bending as shown in FIG. 8.The leather panel 14 is formed by applying the same adhesive asdescribed above onto the folded portion 19 and then pressing the leatherpanel 14 and the thickness adjusting member 15 by means of a metal mold21 having a concave portion 20 whose shape is almost equal to the shapeof the thickness adjusting member 15. At this time, the folded portion19 is bent to cover the side face of the thickness adjusting member 15(FIGS. 9 and 10) onto which the folded portion 19 is bonded. The bondingof the panel butt joint is performed by bonding the folded portion 19 ofthe leather panel 14 onto that of the adjacent leather panel 14.

FIGS. 11 to 13 show another structure of the leather panel 14. FIG. 11shows the thickness adjusting member 15 constituted by the shockabsorbing member 17 and two-layered woven fabrics 16 a and 16 binterposing the shock absorbing member 17 therebetween, FIG. 12 showsthe thickness adjusting member 15 constituted by the two-layered wovenfabrics 16 a and 16 b and two-layered shock absorbing members 17 a and17 b which are provided alternately, and furthermore, FIG. 13 shows thethickness adjusting member 15 constituted by three-layered woven fabrics16 a, 16 b and 16 c and the two-layered shock absorbing members 17 a and17 b which are provided alternately. By increasing the woven fabrics 16a, 16 b, the strength of the thickness adjusting member 15 is increasedand the function of protecting the bladder 2 (FIG. 7) is enhanced at thesame time. More specifically, if the ball hits a sharp object so thatthe leather panel 14 is broken, the force is first intercepted by thewoven fabric 16 a. Even if the woven fabric 16 a is broken, the wovenfabric 16 b, and furthermore, the woven fabric 16 c (in case of threelayers) can protect the bladder.

Pentagonal and hexagonal leather panels usually have each side curvedslightly outward in order to cover the spherical surface. In an actualhand stitched ball, the joint of the leather panel is stretched by asewing thread so that a smooth curve is not formed but the periphery ofthe leather panel often presents a waveform in which a thread portionprojects. As shown in FIG. 14, therefore, an irregularity 22 having awaveform can also be formed on the periphery of the leather panel 14.Consequently, it is possible to implement a ball having an appearancewhich is more similar to the hand stitched ball. With such a structure,the edge of the trench of the joint presents an irregularity. Therefore,gripping properties can be improved and aerodynamic characteristics canbe enhanced. The irregularity 22 having the waveform on the periphery ofthe leather panel 14 can be formed by thermal press or high-frequencyworking.

While the description has been given by taking the soccer ball as anexample in the above-mentioned first embodiment, the present inventioncan also be applied to a handball, a volleyball, a playground ball, abasketball, a rugby ball and the like. In case of the handball, theshape of the leather panel is almost the same as that of the soccerball. In case of the volleyball and the playground ball, the shape ofthe leather panel is set to a rectangle having each side curved outward.

Next, description will be given to the results of comparison of thecharacteristics of the ball according to the embodiment of the presentinvention with those of a ball according to the prior art. For a soccerball (number five size) according to the embodiment of the presentinvention, a bladder and a thread winding reinforced layer had aconventional structure. For a leather panel, a peripheral edge portionwas folded toward an inside by 90 degrees. For a thickness adjustingmember, one polyester-cotton mixed spinning fabric and a CR foamingmember were provided. The total thickness of the leather panel and thethickness adjusting member was 5 mm. A trench formed on a butt joint ofthe leather panels had a width of 2.5 mm and a depth of 2 mm. As acomparative example, typical hand-stitched and laminated balls whichhave the same size were used.

Compression test: Table 1 indicates a growth rate (an expansioncoefficient of a circumference) obtained when 33% of compression isrepeated 30,000 times in the direction of the diameter of the ball.

TABLE 1 Type of ball Growth rate (%) Ball according to the embodiment0.60 Hand stitched ball 1.71 Laminated ball 0.55

As is apparent from the Table 1, the ball according to the embodimentpresents a growth rate which is almost equal to the growth rate of thelaminated ball, and the hand stitched ball presents a great growth rate.This means that the ball according to the embodiment and the laminatedball are excellent in durability but the hand stitched ball is inferiorto them. A difference in the durability mainly depends on a differencein a reinforced layer.

Flight test: FIG. 15 shows a flight (in a rectilinear direction)obtained when kicking is performed at a constant initial speed and aconstant angle by means of a kicking machine. The following is apparentfrom the result.

(a) The ball according to the embodiment and the hand stitched ball havegreat flights than the flight of the laminated ball.

(b) The ball according to the embodiment and the hand stitched ball haveflights almost equal to each other.

(c) As compared with the ball according to the embodiment, the handstitched ball and the laminated ball have great movement in a transversedirection. The movement is increased in order of the ball according tothe embodiment, the hand stitched ball and the laminated ball.

The reason why the hand stitched ball has the great movement is asfollows. It is supposed that the shape of the trench of a hand-stitchedportion is ununiform (which is caused by hand stitching) to make adifference in an air resistance depending on the portion of thespherical surface of the ball. On the other hand, in the ball accordingto the embodiment, the work for bonding the leather panel and thethickness adjusting member can be performed by means of a machine.Therefore, the quality of the ball according to the embodiment isstable. Accordingly, the trench of the panel joint has a uniform shape.Consequently, the air resistance is uniform. Thus, it is supposed thatmovement is not caused on a track.

The reason why the laminated ball has a small flight is that the shapeof the trench does not cause the air resistance to be reduced. Thereason why the movement of the track of the laminated ball is great isthat small track stabilizing effects are obtained by the trench. Asdescribed above, the ball according to the embodiment has the greatestflight and the smallest movement. Therefore, it is apparent that theball according to the embodiment is easy for a player to control anduse.

Curve characteristic test FIG. 16 shows a curve characteristic obtainedwhen kicking is performed by rotation at a constant initial speed and aconstant angle using the same kicking machine as described above. Thelaminated ball has extremely great movement in the rectilinear andtransverse directions as compared with the ball according to theembodiment and the hand stitched ball. Therefore, data were omitted. Thefollowing is clear for the above-mentioned two types of balls.

(a) The ball according to the embodiment has smaller movement in therectilinear direction than the hand stitched ball.

(b) The curve rate of the hand stitched ball is a little greater.

By this result, it is clear that the ball according to the embodimenthas the curve characteristic which is slightly poorer than the curvecharacteristic of the hand stitched ball but has a small variation in alanding area. In an actual game, such a difference in the curvecharacteristic rarely matters. It is more important that the variationin the landing area should be stable. Once the player recognizes thecurve characteristic of the ball, he (or she) can perform control.However, the player cannot predict the movement of the flight.

There has been described the case where a thread winding reinforcedlayer having a conventional structure, that is, a reinforced layerobtained by winding about 3000 m of a nylon filament around the bladdersurface in every direction to give sphericity, spherical maintenance,strength and durability to the ball is used for the reinforced layer ofthe ball in the above-mentioned test. Also in the case where areinforced layer which is obtained by sticking or sewing theabove-mentioned woven fabrics together to take the spherical shape andgives the above-mentioned characteristics, and furthermore, a bladderhaving its own reinforcing function are used, almost the same resultscan be obtained. It is important that the reinforced layer is formedalmost uniformly over the whole bladder surface and the ball istherefore excellent in sphericity and shape maintenance thereof. Inaddition to such a premise, by using the leather panel according to thepresent invention, the flight can be enhanced, the flight can bestabilized and the curve characteristics can be stabilized as describedabove.

In one embodiment of the present invention, the quality such assphericity, shape maintenance, durability or the like is kept equivalentto the quality of the laminated ball, and the leather panel joint hasthe trench having the same shape as in the hand stitched ball.Consequently, the air resistance can be reduced and the flight can beincreased. Moreover, the trench causes the ball to be easy to grip.Therefore, operability and ball controllability can be enhanced.Furthermore, the surface of the leather panel presents a smooth sphere.Therefore, a product can become attractive. Furthermore, since the ballaccording to the present invention basically has a laminated ballstructure, it can be mechanically manufactured. Consequently, stablequality and low cost can be achieved.

In one embodiment of the present invention, water can be prevented fromentering from the joint of the leather panels. In addition, the peelingof the leather panel can be prevented so that durability can beenhanced.

In one embodiment of the present invention, the peripheral edge of theleather panel to achieve the ball surface which is usually polygonal andhas each side curved slightly outward can easily be folded toward theback side. Consequently, there is no possibility that the sphericitymight be deteriorated and irregularities might be generated on the jointof the leather panels.

In one embodiment of the present invention, at the same time that thestrength of the leather panel itself is increased, the bladder isprotected. Therefore, also in the case where external force to break theleather panel is applied to the ball, the bladder is rarely damaged.

In one embodiment of the present invention, a great shock absorbingfunction can be obtained. When the ball hits a human body, a shock canbe relaxed and pains can be relieved to get a soft feeling.

In one embodiment of the present invention, the woven fabric can protectthe shock absorbing member and the bladder which are provided on theinside thereof. Furthermore, it is possible to obtain the shockabsorbing function by the shock absorbing member.

In one embodiment of the present invention, the foaming member, thenonwoven fabric, the bulky woven fabric or the honeycomb constructionmember has light weight. Therefore, the weight of the ball itself can bereduced, and it is possible to obtain a shock absorbing and relievingfunction which is more excellent in the cushioning properties of theball.

A ball for a ball game according to the present invention has highdurability and low cost. Therefore, the ball is useful for physicaleducation and club activities of school, that is, practice as well asregular games such as the Olympic Games.

What is claimed is:
 1. A ball for a ball game comprising: an elasticbladder having a form of a generally spherical hollow body into whichcompressed air is charged; a cover rubber layer formed on a surface ofthe bladder; and a plurality of leather panels bonded onto the coverrubber layer, wherein a peripheral edge portion of each leather panel isfolded toward an inside, a reinforced layer bonded onto a back of theleather panels, and a thickness adjusting member contacting thereinforced layer and being surrounded by the folded portion of theleather panel.
 2. The ball for ball game of claim 1, wherein theperipheral edge portion of the leather panel is folded toward the insideby about 180 degrees.
 3. The ball for ball game of claim 1, wherein theperipheral edge portion of the leather panel is folded toward the insideby about 90 degrees.
 4. The ball for ball game of claim 1, 2 or 3,wherein the leather panel is bonded in the joint with the adjacentleather panel.
 5. The ball for ball game of claim 2, wherein a notch isformed in the folded portion of the leather panel.
 6. The ball for ballgame of claim 1, wherein the thickness adjusting member is made of awoven fabric.
 7. The ball for ball game of claim 1, wherein thethickness adjusting member is made of a shock absorbing member.
 8. Theball for ball game of claim 1, wherein the thickness adjusting memberhas a lamination structure of a woven fabric and a shock absorbingmember.
 9. The ball for ball game of claim 7 or 8, wherein the shockabsorbing member is formed of a foaming member, a nonwoven fabric, abulky woven fabric or a honeycomb construction member.
 10. The ball forball game of claim 1, wherein the reinforced layer is made of apolyester film, a PVC film, a polyethylene film or a polypropylene film.11. A ball for a ball game comprising: an elastic bladder having a formof a generally spherical hollow body into which compressed air ischarged; a first reinforced layer formed on a surface of the bladder; acover rubber layer formed on a surface of the first reinforced layer;and a plurality of leather panels bonded onto the cover rubber layer,wherein a peripheral edge portion of each leather panel is folded towardan inside, a second reinforced layer bonded onto a back of the leatherpanels, and a thickness adjusting member contacting the reinforced layerand being surrounded by the folded portion of the leather panel.